Most of the cell division proteins of walled prokaryotes are absent in the wall-less bacterium Mycoplasma pneumoniae, with the exception of a considerably divergent homolog of FtsZ, which forms a ring at the cell division site in other organisms. We reason that if M. pneumoniae FtsZ functions in cytokinesis, it must do so independently of the other activities that are associated with FtsZ in other organisms, perhaps in association with a different set of proteins; M. pneumoniae FtsZ therefore must have novel properties. In order to begin to elucidate the mechanism of M. pneumoniae cell division at the molecular level, the FtsZ homolog of M. pneumoniae will be expressed in and purified from E coli. The purified protein will be localized in situ in mycoplasma cells. Furthermore, purified recombinant FtsZ protein will be characterized for nucleotide affinity, kinetics of nucleotide hydrolysis, and its polymerization, in order to enable comparison of these properties with those of the FtsZ homologs of other organisms. Finally, proteins that interact with M. pneumoniae FtsZ will be sought.